Core structure for dynamoelectric machines



CORE STRUCTURE FOR DYNAMOELECTRIC MACHINES Filed llarch 14, 1940 l 'il WITNESSES:

'INVENTOR wz Sabn/telden w09@ ATTORNEY Patented Mar. 25, 1941 UNITED STATES PATENT MAC Kurt Schnfelder, Berlin-Char] ottenburg, Germany, assignor to Westinghouse Electric &

Manufacturing Company,

East Pittsburgh, Pa.,

a corporation of Pennsylvania Application March 14,

In Germany De 15 Claims.

The rotor and stator co machines are usuali which are assembled gether to form a l The stator laminati 10 teeth on their inner laminations are circ outer peripheries, s sembled the teeth r slots in which the l such a machine is and magnetic forces jected cause the c teeth, to vibrate circ res of dynamoelectric y built up of laminations, in a stack and clamped toaminated cylindrical core. ons are annular and have peripheries, while the rotor ular and have teeth on their o that when the core is asform generally longitudinal windings are placed. When in operation, the electrical to which the cores are subore, and particularly the umferentially. This vibration is undesirable and produces considerable noise in the operation of the machine which is very objectionable. Attempts have been made to reduce this vibration by selecting particular relations of the slot` pitches in the rotor and stator, and by using different numbers of slots per pole per phase in the rotor and stator, but these methods are not satisfactory since they have only a limited eect in reducing the vibration, and they are not applicable to all machines.

'I'he object of the present invention is to provide a core construction for dynamoelectric machines in which the vibration of the teeth is substantially eliminated, or at least greatly reduced, so that the objectionable noise during operation of the machine is also greatly reduced.

More specifically, the object of the invention is to reduce or suppress vibration of the teeth of a laminated core structure by forming them so that the natural frequencies of Vibration are low and so that the internal consumption of energy in the teeth during vibration is very large. The large consumption of energy during vibration has a very strong damping effect which reduces the amplitude of the Vibration to a very low value, while the low natural frequencies of vibration give low pitched tones so that the greatly reduced Volume of noise produced is of low pitch and is not objectionable.

These results are readily obtained by splitting or otherwise dividing the teeth into parts which are narrower than an undivided tooth and which are in frictional engagement with each other, so that they rub against each other when the tooth vibrates and thus consume a large amount of energy. In this way a strong damping effect is producedwhich greatly reduces the-'amplitude of 1940, Serial No. 323,918 cember 24, 1938 the vibration. Greater tained by splitting the that the two parts ha quencies. This increas noise.

OFFICE effectiveness can be obteeth unsymmetrically so ve different natural frees the frictional rubbing gy consumption, since oth tend to vibrate at nd by this means the completely suppressed, ting the objectionable The invention will be more fully understood from the following detailed description, taken in connection with th which:

Figure l is a of a dynamoelectric ma Fig. 2 is a fragmentar portion of a core memb e accompanying drawing, in

partial longitudinal sectional View chine;

y elevational view of a Fig. 3 is a view similar to Fig. 2 showing the deformation of the Fig. 4 is a fragm core member showin invention;

Fig. 5 is a fragment larged scale of a porti Fig. 4;

teeth during vibration; entar y elevational view of a g another embodiment of the ary plan view on an enn of the core member of Fig. 6 is a somewhat diagrammatic view of the n of windings is supported in a suitable frame showing the deformation ation; and

are fragmentary ele-va- Figs. 2 and 4, showing of the invention. r less diagrammatically the dynamoelectric machine ge size, such as an induction chine has a stator core l comty of ann ular laminations which n a stack to form a cylinthe laminations being groups to provide radial venin the usual manner. e core I have teeth on their The form longitudinal slots 3, and the core structure 4. The

rotor member is secured to a shaft 5 and has a core 6 built up of circu ilar manner to the stator core tions also have peripheral teeth tudinal slots for the rec ing indicated at 1.

Figs. 2 and 3 show scale a construction of the vibration during o lar laminations in a sim- These laminato form longieption of a suitable windon a somewhat enlarged the teeth for core memers of the type shown in Fig. 1 to greatly reduce peration of the machine and thus reduce the noise. a portion of a rotor core 8 having gene-rally radial teeth 9 on its periphery, although it will be understood, of course, that the invention is applicable to both rotor and stator cores. In order to reduce the vibration of the teeth 9, they are divided into parts which are narrower than an undivided tooth and which are in frictional engagement with each other. As shown in the drawing, this These figures show tially equal parts.

The eiect of this construction is shown in Fig;

3, which shows the deformation of the teeth dur-` ing vibration, the deformation being greatly exaggerated for the sake of clearness. VIt'will beV narrower relative to their length than an uns which would be produced by a divided tooth, the natural frequency of vibration of each part is lower than that of an undivided tooth and, therefore, the noise caused by vibration of the split teeth is lower in pitch than that tooth of the usual construction. Such low pitched tones are much less objectionable than the high pitched, penetrating tones caused by vibration of conventional teeth. Thus, it will be seen that the construction of Figs. 2 and 3 is effective to improve the operment the teeth II of a ycore member ation of a machine in which this'core structure is used by greatly reducing the amplitude of vibration of the teeth so that the noise during operation of the machine is greatly reduced in volume, and also that the small amount of noise which still occurs is relatively low pitched and is not objectionable.

A still more effective embodiment of the invention is shown in Figs. 4, 5 and 6. In this embodi- IZ are split unsymmetrically at I3, a desirable ratio for the widths of the two parts of the tooth being 65:35. Successive laminations are disposed in the stack so that the splits in corresponding teeth are oiset from each other in order to cause the wider portions of corresponding teeth of successive laminations to overlap as shown in Fig. 5, which is an enlarged plan view of a portion of a single tooth. The effect of this construction is shown in Fig.

6, which is a somewhat diagrammatic View showeffect on the vibration.

ing the deformation of the teeth during vibration, the deformation being greatly exaggerated. As before, the two parts of each tooth rub o-n each other along the split I3 and cause a damping In addition, the wide parts of corresponding teeth of successive laminations overlap each other and are in frictional engagement, as indicated by the shaded areas I4 in Fig. 6. The rubbing action in these areas between the adjacent laminations also has a very strong damping effect, so that the amplitude of the vibrations is very materially reduced. Since each tooth is divided into parts of unequal widths, the two parts have different natural frequencies and tend to vibrate at different frequencies, so that the effectiveness of the rubbing action beis most conveniently done by splitting each tooth in a radial direction, as` indicated at II), to divide it into two substanthere is a relativeproduces a very strong' tween them in damping the vibrations is greatly increased. Any tendency towards vibration axially of the core is effectively suppressed because of the very great frictional rubbing action which would occur due to the different amount of deformation of the tooth portions. It will be apparent, therefore, that this embodiment of the invention is very effective in greatly reducing the amplitude of the vibrations because of the strong damping action caused by the rubbing between the two parts of each tooth which tend` to vibrateat dierent frequencies, and also because of the rubbing action between the overlapping parts of corresponding teeth of adjacent laminations. In this way the amplitude of the vibrations is reduced to a Very small value and the noise caused by it is correspondingly reduced.

Another embodiment of the invention is shown in Fig. 7. In this form of the invention, the teeth I5 are split as indicated at I6 in the same manner as in Fig. 2, but the teeth of adjacent laminations are split to different radial depths, the split in the teeth of the next adjacent lamination being shown dotted at I1 in Fig. 7. In the assembly of a complete core, the laminations with deeper splits are alternated with those having shorter splits so that the teeth of each lamination lie between adjacent teeth which are split to different depths. The effect of this construction is similar to that of Fig. 2 but the dam-ping action is somewhat greater because of the fact that the corresponding teeth of successive laminations have slightly` different natural frequencies and, therefore, tend to vibrate at diierent rates, so that there is a certain amount of frictional rubbing between the adjacent laminations which increases the damping action.

An alternative arrangement is shown in Fig. 8 in which successive teeth I8 of each lamination are split to different depths as indicated at I9 and 2D. In assembling such a core, the adjacent laminations are reversed in position with respect to each other, so that each tooth is in contact with a tooth on the adjacent lamination which is split to a different depth, as indicated at 2| and 22. It will be apparent that the effectV of this arrangement is the same as that of Fig. 7 in damping the vibrations.

Still greater eiectiveness can be obtained and vibration of the teeth almost completely eliminated by suitable combinations of the constructions described above. rThus, in Fig. 9 there is shown a combination of the constructions of Figs. 4 and 7. In this figure, each tooth 23 is split unsymmetrically at 24, while the teeth of adjacent laminations are split to different radial depths, as indicated at 25, and the laminations are arranged as in Fig. 4 so that the splits in corresponding teeth of adjacent laminations do not coincide. The effect of this arrangement is similar to that of Fig. 4 in that the two parts of each tooth have different natural frequencies, so that a very strong damping action is obtained by the frictional rubbing between them, while rthe overlapping parts of corresponding teeth on adjacent symmetrically at 21, and the successive teeth of each lamination are split to different i radial depths. Adjacent laminations are reversed with respect to each other as in Fig. 9, so that the splits in corresponding teeth do not coincide, the teeth of the adjacent lamination being split at 28. It will be apparent that the eiect of this arrangement is the same as that of Fig. 9, and that the vibration will be substantially completely suppressed because of the very strong damping action which is obtained by this arrangement.

It should now be apparent that a construction has been provided for the core members of a dynamoelectric machine in which the vibration of the teeth of the core during operation of the machine is substantially suppressed, or at least very materially reduced, so that the noise caused by the machine during operation is reduced to a very small volume which is not objectionable. Several specific embodiments of the invention have been disclosed, but it is to be understood that various other constructions could also be used for damping the vibration of the teeth and lowering their natural frequencies. The invention is applicable to both rotor and stator cores and may be used with any type of tooth. It is to be understood, therefore, that the invention is not limited to the particular arrangements shown, but in its broadest aspects it includes all equivalent embodiments and modifications which come within the scope of the appended claims.

I claim as my invention:

1. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being divided into partsI which are in frictional engagement with each other to cause a strong damping eiect on vibration of the teeth.

2. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being divided into parts which have a lower natural frequency than that of an undivided tooth, said parts being in frictional engagement with each other to cause a strong damping effect on vibration of the teeth.

3. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction into two parts which are in frictional engagement with each other.

4. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, said parts being in frctional engagement with each other.

5. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, adjacent laminations being disposed so that the `splits in their teeth are displaced from each other.

6. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, the teeth of adjacent laminations being arranged so that the wider part of a tooth of one lamination overlies the narrow part of the corresponding tooth of the successive lamination.

7. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction, the teeth of diierent laminations being split to different radial depths.

8. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction, successive teeth of said lamination being split to different radial depths.

9. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction, successive teeth of each lamination and corresponding teeth of adjacent laminations being split to different radial depths.

10. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, the teeth of different laminations being split to diierent radial depths.

1l. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, successive teeth of each lamination being split to dilerent radial depths.

l2. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed 'in a stack to form a cylindrical core, each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal Width, successive teeth of each lamination and corresponding teeth of adjacent laminations being split to dierent radial depths.

13. A core structure for a dynamoelectric machine comprising a plurality of laminations disposed in a stack to form a cylindrical core, each of said laminations having Iteeth on its periphery forming slots between them, and each of said teeth being split in a radial direction to divide the tooth into two parts of unequal width, adjacent laminations being disposed so that the splits in their teeth are offset from each other,

and the teeth of adjacent laminations being split to different radial depths. e

14. A core structure for a dynamoelectric machine comprising a plurality of laminations Adisposed in a stack to form a cylindrical core,

each of said laminations having teeth on its periphery forming slots between them, and each of said teeth being split in a radial .direction to divide the tooth into two parts of unequal width, adjacent laminations being disposed so that the splits in their teeth are offset from each other, and successive teeth of each lamination being split to `different radial depths.

riphery forming slots between them, and each of said teeth being split in a radial direction to `divide the tooth into two parts of unequal Width,

adjacent laminations being disposed so that the splits in their teeth'are offset from each other,

successive teeth of each lamination and corresponding teeth of ladjacent laminations being split to different radial depths.

KURT SCHONFEIDER. 

